There are known cross-linked fluorinated resins of the epoxy type prepared starting from epichlorohydrin, a fluorinated bisphenol and a fluorinated diol of formula: EQU HO(CF.sub.3).sub.2 CCH.sub.2 CH.dbd.CHC(CF.sub.3).sub.2 OH,
(U.S. Pat. No. 4,132,681. However, such cross-linked resins exhibit rather low thermal, chemical and photochemical stabilities and are difficult to prepare.
Known too and described in U.S. Pat. No. 3,810,874 are fluorinated polyoxides cross-linkable with amines; however, said polymers, after cross-linking has occurred, do not possess satisfactory mechanical characteristics, such as hardness, tensile strength, modulus of elasticity, elongation.
Therefore, the polymers of the prior art are not suitable for particular uses, such as e.g. printed circuits, in which the coating polymer has to guarantee, along with exceptional characteristics of stability to heat and to solvents, also a high chemical stability, as well as high mechanical properties, even at very high temperatures.
Thus, there was the requirement to produce highly cross-linked epoxy-type resins exhibiting improved mechanical properties and offering, in particular, applicative advantages as compared with already known analogous products.